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United States Patent |
5,199,574
|
Hollyfield, Jr.
,   et al.
|
April 6, 1993
|
Vibrating screen separator
Abstract
A vibrating screen separator comprising a tuned suspension system for
controlling a sifting screen and a resiliently isolated vibrator drive
system for efficiently vibrating the screen cloth. The separator may be
configured with stacked decks and serially connected sections involving
multiple cooperating sifting planes. A rigid frame inclined above a
supportive surface suspends the cloth for sifting material. The cloth is
tensioned between frame sides by mounting rails, and it overlies a
reinforcing subframe. The rails are tensioned by eye nuts externally
accessible at the sides of the frame. Material gravitationally flows over
the vibrating screen towards the discharge end. The cloth is shaken by an
elongated, center strip aligned with the direction of material travel. The
center strip is oscillated by the vibrator drive system disposed above it,
which is coupled thereto by linkage. The tuned suspension system comprises
a pair of generally cylindrical, rubber buffers mounted in shear that
connect each end of the center strip to the subframe. Thus the center
strip ends are resiliently isolated relative to the subframe. Through this
arrangement vibrations are uniformly distributed throughout the surface
area of the cloth. The vibrator drive system comprises a rotary, electric
vibrator mounted in shear by sets of rubber buffers. The axis of rotation
of the motor is aligned with the direction of material travel.
Inventors:
|
Hollyfield, Jr.; Clifford G. (Rosewll, GA);
Jackson; Allen S. (Atlanta, GA)
|
Assignee:
|
J & H Equipment, Inc. (Roswell, GA)
|
Appl. No.:
|
785523 |
Filed:
|
October 31, 1991 |
Current U.S. Class: |
209/315; 209/365.1; 209/409 |
Intern'l Class: |
B07B 001/28 |
Field of Search: |
209/315,364,365.1,408,409,412,419
|
References Cited
U.S. Patent Documents
1606558 | Nov., 1926 | Clark | 209/365.
|
1610353 | Dec., 1926 | Bland | 209/315.
|
1769413 | Jul., 1930 | Binte et al. | 209/409.
|
2636605 | Apr., 1953 | Wilson | 209/409.
|
2920762 | Jan., 1960 | Muller et al. | 209/365.
|
3325007 | Jun., 1967 | Erlenstadt et al. | 209/315.
|
4319993 | Mar., 1982 | Krause | 209/412.
|
4840728 | Jun., 1989 | Connolly et al. | 209/409.
|
4848607 | Jul., 1989 | Halley | 209/412.
|
Foreign Patent Documents |
0899156 | Jan., 1982 | SU | 209/408.
|
1235555 | Jun., 1986 | SU | 209/365.
|
1264999 | Oct., 1986 | SU | 209/365.
|
9105617 | May., 1991 | WO | 209/365.
|
Primary Examiner: Olszewski; Robert P.
Assistant Examiner: Bidwell; James R.
Attorney, Agent or Firm: Carver; Stephen D.
Claims
We claim:
1. A vibrating screen separator comprising:
a material input end and at least one spaced apart material discharge end,
wherein material travels from said input end towards said discharge end;
a rigid, elongated frame adapted to be disposed upon a supporting surface,
said frame comprising a pair of spaced apart sides;
a generally planar, mesh screen comprising a pair of sides tensioned in
spaced apart relationship substantially within said frame and transversely
with respect to the direction of material travel;
elongated strip means for directly contacting and vibrating said screen,
said strip means oriented in spaced apart, generally parallel relation
with respect tot said frame sides in substantial alignment with the
direction of material travel;
tuned suspension means for resiliently securing said strip means relative
to said frame for uniformly distributing screen vibration, said tuned
suspension means comprising buffers at each end of said strip means for
resiliently securing opposite ends of said strip means to said frame; and,
dynamic vibrator drive means for vibrating said strip means and thus said
screen, said vibrator drive means comprising a vibrator having an axis of
rotation generally parallel with the direction of material travel and
means for resiliently mounting said vibrator vertically spaced apart from
said screen, said dynamic vibrator drive means comprising:
a first mounting plate to which said vibrator is firmly attached;
a second mounting plate secured relative to said frame; and,
an symmetric array of buffers for resiliently coupling said first mounting
plate to said second mounting plate.
2. The separator as defined in claim 1 wherein:
said separator comprises a generally rectangular subframe received within
said frame for bracing same said subframe mounting said screen; and,
said buffers are connected to opposite ends of said subframe.
3. The separator as define din claim 2 further comprising bridge means
extending transversely across said frame above said screen for securing
said second mounting plate.
4. The screen separator as defined in claim 3 further comprising connector
means extending from said vibrator through said second mounting plate to
said strip means for transmitting vibration to said strip means.
5. The screen separator as defined in claim 4 wherein said connector means
is flat and flexible, and said connector means occupies a plane
substantially coincident with the direction of material travel and
substantially parallel with said axis of rotation, whereby torsional
displacements of said connector means are resisted and proper screen
control is achieved.
6. The vibrating screen separator as defined in claim 2 wherein said first
mounting plate comprises a first flange and a second flange having a
greater area than said first flange, said second mounting plate comprise a
third flange and a fourth flange having a greater area than said third
flange, said first flange being resiliently coupled to said third flange
by a predetermined number of resilient buffers, and said second flange
being resiliently coupled to said fourth flange by a larger number of
buffers.
7. The vibrating screen separator as defined in claim 6 wherein said first
and third flanges face said input end, said second and fourth flanges face
said discharge end, and each of said flanges defines a plane substantially
perpendicular to said axis of rotation.
8. A vibrating screen separator comprising:
a material input end and at least one spaced apart material discharge end,
wherein material to be sifted travels from said input end towards said
discharge end;
a rigid, generally rectangular subframe adapted to be removably coupled to
said separator, said subframe having a pair of spaced apart sides and a
pair of spaced apart ends transversely extending between said sides;
a generally planar, mesh screen adapted to be disposed within said
separator above said subframe to form a sifting plane over which material
is passed for separation, said screen comprising a pair of sides tensioned
in spaced apart relationship and a pair of opposite ends;
elongated strip means for directly contacting and vibrating said screen,
said strip means oriented in spaced apart, generally parallel relation
with respect to said subframe sides substantially at the screen center,
said strip means comprising a pair of opposite ends generally coincident
with said screen ends, and said strip means substantially aligned with the
direction of material travel;
tuned suspension means for resiliently securing said strip means relative
to said subframe for uniformly distributing screen vibration, said tuned
suspension means comprising at least one resilient buffer secured to each
end of said strip means and to ends of said subframe; and,
dynamic vibrator drive means for vibrating said strip means and thus said
screen, said vibrator drive means comprising a rotary vibrator
establishing an axis of rotation parallel with the direction of material
travel and means for asymmetrically resiliently mounting said vibrator;
connector means for interconnecting said strip means with said vibrator
drive means for vibrating said strip means and thus said screen.
9. The screen separator as defined in claim 8 wherein:
said dynamic vibrator drive means comprises a first mounting plate to which
said vibrator is firmly attached and a second mounting plate secured
relative to said frame; and,
wherein said means for asymmetrically resiliently mounting said vibrator
comprises a plurality of buffers coupling together said first and second
mounting plates.
10. The separator as defined in claim 9 further comprising bridge means
extending transversely across said machine above said screen for securing
said second mounting plate.
11. The screen separator as defined in claim 9 further comprising connector
means extending from said vibrator through said second mounting plate to
said strip means for transmitting vibration to said strip means.
12. The screen separator as defined in claim 11 wherein said connector
means is flat and flexible, and said connector means occupies a plane
substantially coincident with the direction of material travel and
substantially parallel with said axis of rotation, whereby torsional
displacements of said connector means are resisted and proper screen
control is achieved.
13. The vibrating screen separator as defined in claim 11 wherein said
first mounting plate comprises a first flange and a second flange having a
greater area than said first flange, said second mounting plate comprise a
third flange and a fourth flange having a greater area than said third
flange, said first flange being resiliently coupled to said third flange
by a predetermined number of resilient buffers, and said second flange
being resiliently coupled to said fourth flange by a larger number of
buffers disposed in an offset configuration relative to said last
mentioned predetermined number of resilient buffers.
14. The vibrating screen separator as defined in claim 13 wherein said
first and third flanges face said input end, said second and fourth
flanges face said discharge end, and each of said flanges defines a plane
substantially perpendicular to said axis of rotation.
15. A dynamic vibrator drive system for vibrating screen separators of the
type comprising a material input end and at least one spaced apart
material discharge end, a generally planar, mesh screen comprising a pair
of sides tensioned in spaced apart relationship substantially within said
separator, and wherein material travels from said input end towards said
discharge end, said drive system comprising:
a rotary vibrator establishing an axis of rotation substantially aligned
with the direction of material travel;
resilient means for asymmetrically mounting said vibrator vertically spaced
apart from said screen;
means for directly contacting said screen; and,
connector means extending between said screen contacting means and said
vibrator.
16. The system as defined in claim 15 wherein said dynamic vibrator drive
system comprises:
a first mounting plate to which said vibrator is firmly attached;
a second mounting plate secured relative to said system; and,
an asymmetric array of buffers for resiliently coupling said first mounting
plate to said second mounting plate.
17. The system as defined in claim 16 further comprising bridge means for
extending transversely across said separator above said screen for
securing said second mounting plate.
18. The system as defined in claim 17 wherein said connector means is flat
and flexible and occupies a plane substantially coincident with the
direction of material travel and substantially parallel with said axis of
rotation, whereby torsional displacements of said connector means are
resisted and proper screen control is achieved.
19. The system as defined in claim 16 wherein said first mounting plate
comprises a first flange and a second flange having a greater area than
said first flange, said second mounting plate comprise a third flange and
a fourth flange having a greater area than said third flange, said first
flange being resiliently coupled to said third flange by a predetermined
number of resilient buffers, and said second flange being resiliently
coupled to said fourth flange by a larger number of buffers.
20. The system as defined in claim 19 wherein said first and third flanges
face said input end, said second and fourth flanges face said discharge
end, and each of said flanges defines a plane substantially perpendicular
to said axis of rotation.
21. A vibrating screen separator comprising:
a material input end and at least one spaced apart material discharge end,
wherein material travels from said input end towards said discharge end;
a rigid, elongated frame adapted to be disposed upon a supporting surface,
said frame comprising a pair of spaced apart sides;
a generally planar, mesh screen comprising a pair of sides tensioned in
spaced apart relationship substantially within said frame and transversely
with respect to the direction of material travel;
a generally rectangular subframe received within said frame for mounting
said screen;
elongated strip means for directly contact and vibrating said screen, said
strip means oriented in spaced apart, generally parallel relation with
respect to said frame sides in substantial alignment with the direction of
material travel;
tuned suspension means for resiliently securing said strip means relative
to said frame for uniformly distributing screen vibration, said tuned
suspension means comprising buffers at each end of said strip means for
resiliently securing opposite ends of said strip means to ends of said
subframe;
dynamic vibrator drive means for vibrating said strip means and thus said
screen, said vibrator drive means comprising a vibrator establishing an
axis of rotation generally parallel with the direction of material travel
and means for resiliently mounting said vibrator vertically spaced apart
from said screen, said dynamic vibrator drive means comprising:
a first mounting plate to which said vibrator is firmly attached;
a second mounting plate secured relative to said frame; and,
an asymmetric array of buffers for resiliently coupling said first mounting
plate to said second mounting plate.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to vibrating screen separator systems.
More particularly, this invention relates to an improved vibrating screen
system and an improved dynamically tuned suspension system for
operationally mounting the vibrator and agitating the screen.
The prior art reflects numerous attempts at screen separators. In a typical
screen separator, an elongated, box-like like frame of upright rigid
characteristics is inclined over a supporting surface, and a screen
captivated within the frame is vigorously shaken as material passes over
it. Critically sized material drops through the screen, for conveyance to
alternative separators or product bins and the like. A variety of
different vibrators, including pneumatic, hydraulic, and rotary types,
have been used.
In some prior art designs vibration is applied directly to the frame or a
large, usually heavy subframe containing the screen. U.S. Pat. No. 4,
274,953 issued Jun. 23, 1981, and owned by the same assignee as in the
instant case discloses a rigid supportive frame that is dynamically
interconnected with an upper vibrating subframe. The mass of the entire
screen subframe must be vibrated to appropriately shake the screen
elements. As a consequence, a relatively large mass must be vibrated. Such
designs are inappropriate for many applications since they waste
considerable energy, and they tend to wear out critical parts because of
the stresses and movements they involve.
Examples of typical prior art screening machines are seen in U.S. Pat. Nos.
4,882,054, 4,065,382 and 4,839,036. The latter reference mounts the
screens on removable frames, which are directly shaken by pushers attached
to vibrators therebelow. U.S. Pat. No. 4,065,382 discloses vibrating
screen apparatus in which the screen device is maintained within a number
of removable subframes, and the subframes are directly shaken by the
vibrator apparatus. U.S. Pat. No. 3,630,356 discloses a system wherein a
subframe of relatively rigid characteristics is independently vibrated by
a lower beam.
Prior art attempts also have been made at shaking and vibrating the
separating screen directly. Typical of vibrating screening machines of the
latter type are Johnson patent 3,442,381 and Feller patent 3,825,118. Hahn
patent 3,693,793 attempts to vibrate the screen by gyratory action. U.S.
Pat. No. 3,642,133 shows a vibrating screen assembly in which a plurality
of subframe screens is mounted sequentially within a frame, and each of
the subframes is vibrated independently. Other attempts at vibrating
screen systems are seen in U.S. Pat. Nos. 4,340,469; 4,180,458; 4,840,728;
4,855,039; 4,826,017, 3,756,407; and 3,468,418.
Numerous patents disclosing screens suitable for screen vibrating
separators exist. For example, U.S. Pat. Nos. 4,491,517; 4,575,421;
4,819,809, and others are known in the art.
As will be appreciated, the screening effectiveness of a vibrating wire
screen is a function of gravity and the movement of material relative to
the wire screen. Too little movement of the particles will allow them to
wedge in the wire cloth, too much movement will bounce the particles
excessively and greatly reduce the screening capacity while also raising
the dust level. The conveying capacity of a material on a vibrating wire
screen is a function of slope, amplitude, frequency, load, and flow
characteristics of the material. The optimum flow, amplitude, frequency,
and slope relation would be one that loads the wire cloth with the maximum
amount of material, but does not impede the free movement of the material.
An increase in the slope or the machine or amplitude or frequency of
vibration, or a reduction of the load will increase the free movement of
the material.
One problem with known prior art screen separator machines is that the
input of relatively large amounts of vibrational energy tends to damage
the screening cloth, particularly along the mounting edges. The more
energy that is inputted to a vibrating system, the greater the possibility
of fatigue and destruction as time progresses. When the vibrational forces
are poorly distributed about the surface of the screen, and the amount of
total force necessary is aggravated. In other words, to provide functional
separating along those sections of the screen that were vibrating less, a
greater amount of energy must be applied at the input point. All vibrating
wire screening machines will show varying amplitude rates across the face
of the wire cloth (i.e., loops and nodes). The position of these loops and
nodes will vary with the type of wire and wire tension.
It is known to provide a center strip of cross metal strips on a screen,
and known prior art systems also have employed center strips for screen
attachment that floated. Such center strips in prior art attachment
designs for attaching the vibrational motor to the screen have hitherto
generated poorly distributed energy patterns. In other words, the
vibrational energy hitherto imparted to vibrating screens has been poorly
distributed. Winquist U.S. Pat. No. 3,491,881 has this problem of
vibrating too much mass.
U.S. Pat. No. 4,430,211 attempts to remedy the problem of vibrating mass by
concentrating vibrations to a separate screen deck. Another attempt at
aiming vibration direction at the screen subassemblies is seen in U.S.
Pat. No. 3,520,408. The latter patent reference attempts to periodically
contact and vibrate the screen directly by suitable crosspieces that
contact the critical screen transversely to the direction of travel. While
the latter approach is certainly a good one, in that less energy must
generally be expended in vibrating a screen directly, rather than
vibrating the whole frame or the subframe, such devices are characterized
by other well known problems.
For example, it is very difficult to obtain uniform distribution of force
energy upon the surface of the screen. Failure to properly distribute the
energy vibrations will result in regions of high vibration separated from
regions of low vibrations. The inefficiency of material handling equipment
characterized by irregular vibration patterns is well known. Moreover,
unless the forces are balanced and properly distributed, wear and tear
upon vibrated components will lead to early failure and increase the
required maintenance. Therefore the primary problem is to try to find a
way to minimize energy input, but when energy input is minimized, energy
must be properly distributed. The difficulties in distributing energy
properly along the screen can be compounded by the weight factors of the
material being handled, so a resilient and capable system for applying
force to the screen, in a non-destructive fashion is necessary.
We have determined to optimize the interconnection of the screen-contacting
assembly, along with the orientation and mounting of the vibrational motor
system, in such a way to minimize energy inputs, maximize part and
component life, while at the same time widely distributing force in an
even non-destructive fashion. Therefore, it is important to provide a
suspension system for vibrating screen separators in which the energy
imparted by the motor connection with the screen is distributed evenly
throughout the surface of the screen. The driven area should internally
radiate vibrations throughout the total surface of the screen, to
homogeneously distribute the force, without overtensioning or
overstressing the particular screen areas. Through this approach we have
determined that less energy is required to drive the cloth, because the
uniformity of vibration amplitude throughout the cloth surface is
achieved. The tuned suspension minimizes the amplitude variations to give
maximum screening effectiveness.
SUMMARY OF THE INVENTION
Our screen separator machine comprises a unique tuned suspension system for
controlling the vibrating sifting cloth, and a dynamic vibrator drive
system that isolates the motor and efficiently vibrates the cloth. It can
be configured in a plurality of different operational configurations
involving stacked decks and serially connected sections, necessitating
various combinations of suspension systems and vibrator drive systems.
A typical machine comprises a rigid, generally rectangular frame adapted to
be inclined above a supportive surface at between thirty to forty degrees.
Material to be sifted enters a material input end of the machine, and is
directed into a uniform flow of materials that travel gravitationally
towards the material discharge end for escape through various output
chutes.
The frame comprises a pair of rigid, spaced apart sides bordering an
internal screen receptive region. Preferably a removable subframe is
centered within the latter region of the frame. The subframe reinforces
the main frame when the cloth is tensioned. A sifting plane established
within the frame above the subframe comprises wire mesh cloth tensioned
between the frame sides by suitable mounting rails. Multiple sifting
planes are associated with multiple deck, multiple section arrangements.
Besides resisting frame deformation, the subframe insures that the wire
cloth is tensioned uniformly. User accessible eye nuts disposed at the
screen sides may be conveniently adjusted to properly tension the rails
and thus the screen cloth.
The middle of the screen cloth is sandwiched by a vibrating center strip
that longitudinally extends along the middle of the screen, aligned with
the direction of material travel. The strip is substantially centered with
respect to the screen, the subframe, and the frame sides. The center strip
is mechanically oscillated by a vibrator drive system preferably disposed
above it, which is coupled thereto by one or more flexible links. The
center strip is yieldably mounted by a tuned suspension system comprising
buffers that resiliently secure the strip ends relative to the frame.
The tuned suspension system preferably comprises pairs of generally
cylindrical, rubber buffers mounted in shear to the subframe adjacent each
end of the center strip. Suitable plates secured to opposite ends of the
buffers are mechanically secured to the center strip ends. Through this
arrangement vibrations are uniformly distributed throughout: the surface
areas of the cloth. The ends of the center strip terminate in resilient
buffers, rather than terminating in direct mechanical contact with the
frame or subframe. As a result, oscillations at the ends of the screens
are not severely attenuated. At the same time what would have been
reflected, unbalanced energy is distributed throughout the screen cloth
surface area more uniformly.
Screen vibration is caused by a vibrator drive system preferably mounted on
top of the frame. An electric vibrator is mounted on rubber buffers
operating in shear. The shear mounting allows the vibrator motor to
produce the required vibration with a minimum of eccentric weight. In the
best mode three separate buffers are mounted on the material discharge end
and a single buffer is employed at the material input end. This buffer
orientation compensates for asymmetrical loading created by the inclined
orientation. In addition, this vibrator orientation functions
synergistically in cooperation with the strip suspension system to
generate ideal vibration distribution patterns.
Energy patterns observed with our design evidence the uniform distribution
of vibrational energy upon almost the entire cloth surface. Not only is
vibration more uniformly distributed on the cloth with our design, but it
is more effectively isolated from the frame and subframe. As a result,
vibration-induced stresses are reduced. Overall machine reliability and
component life are enhanced.
Thus a basic object of the present invention is to provide a highly
reliable and cost effective screening machine for use in a wide variety of
screening applications.
A basic object of our invention is to focus and control vibration in a
screen separator machine.
Another object is to provide a dynamic suspension system that enhances
energy distribution on the sifting plane.
A related object is to provide a vibrator drive system for screen
separators that isolates vibration from the frame and concentrates it upon
the cloth.
Another object is to minimize the number of required moving parts in a
screening machine, to minimize the quantity of parts that require
maintenance or periodic replacement.
Another basic object of our invention is to provide a screening machine of
the character described which imparts relatively large amounts of
vibrational energy to the screening cloth with a low amplitude stroke. It
is a feature of the invention that the reduced amplitude stroke due to the
tuned suspension construction reduces the possibility of fatigue and
breakage of the vibrating parts.
Still another object of the present invention is to provide a screening
machine of the character described having an extremely low noise level. It
is a feature of the invention that machines constructed in accordance with
the teachings herein exhibit a noise level less than OSHA requirements 85
dbA.
Yet another object of the present invention is to provide a screening and
vibrating machine of the character described which maintains the motor in
a fixed position even if linkage breaks. It is a feature of the present
invention that motors are mounted in sheer on separate rubber buffers in
the configuration for maximum safety.
Another important object of the present invention is to provide a
dynamically tuned suspension system for vibrating screening machines of
the character described in which the wave pattern avoids tensioning and
flexing of the connecting arm where the screen is attached.
Another essential object is to provide a dynamic tuned suspension for
screening machines of the character described in which sign wave energy is
transmitted through the connecting arm and maximized upon the separation
screen.
Another object is to reduce the effect of bouncing and tossing in screening
machines of the character described, thereby more efficiently screening
materials.
Yet another object is to provide a multi-sectional tuned suspension
screening machine of the character described in which the screens are so
mounted to allow material to flow from section to section and on to
sequential screens with minimum loss of material due to "dusting."
A still further object is to provide a dynamically tuned suspension system
of the character described which allows sections to be mounted in a common
inclined plane, rather than being "stepped" wherein succeeding vibrating
sections are mounted in planes lower than previous sections.
Still another object of the present invention is to provide a modular tuned
suspension design of the character described in which modules may succeed
each other serially in one inclined plane, or may be stacked above each
other.
A related object is to provide a tuned suspension system of the character
described for modularized deployment, in which vibrating energy may be
imparted to vertically stacked screen members through one upper
vibrational structure.
Yet another object is to provide a screening system of the character
described which reduces plugging, and minimizes noise.
A similar object is to provide a system of the character described in which
the wire cloth may be easily installed. It is a feature of the present
invention that only two bolts per panel must be tightened after the cloth
is in place, which is an especially advantageous feature when using
multiple deck machines.
Another object of the present invention is to provide a tuned suspension
system of the character described in which multiple deck machines are
provided with enough space for inspection and cleaning.
Another object is to provide a system wherein screen cloth tensioning is
accomplished only with the use of convenient eye nuts, thus eliminating
the need for special wrenches and encouraging personnel to properly
maintain the operating tension of the cloth.
A similar object is to provide a vibrating screen of the character
described in which either 1800 or 3600 rpm conventional vibrators may be
employed at the behest of the user for screening.
Another object of the present invention is to provide a dynamic suspension
system that compensates for the angular disposition of the sifting plane.
A basic object is to provide a reliable vibrating screen separation system
of the character described which may be employed with products such as
glass silica, beaded glass, fertilizers, roofing granules, coke for steel
production, clays and various aggregates.
Another object of the present invention is to provide a mounting system for
both the screen vibration strip and the motor system that prevent "bounce
and toss" of the material traveling through the screen, and widely
distributes screen energy throughout its surface area.
Another basic object is to provide a vibrating screen separator assembly of
the character described in which the screen is non-destructively vibrated
directly, so that vibrational energy is efficiently utilized and
homogeneously distributed.
A related object is to provide a screen separator device of the character
described which does not directly impart vibration to the frame. It is a
feature of our machine that the vibrator is isolated from the frame, and
vibrations are transmitted directly to the wire cloth by a center strip
whose ends are buffered to encourage force distribution.
An important object of our invention is to provide a vibrating separator of
the character described which uniformly distributes vibration throughout
the screen cloth surface area.
Another primary object is to provide a separator that exhibits only minimum
structural vibration.
These and other objects and advantages of the present invention, along with
features of novelty appurtenant thereto, will appear or become apparent in
the course of the following descriptive sections.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following drawings, which form a part of the specification and which
are to be construed in conjunction therewith, and in which like reference
numerals have been employed throughout wherever possible to indicate like
parts in the various views:
FIG. 1 is a fragmentary, perspective view of a typical double deck
vibrational screening machine employing our tuned suspension and our
preferred vibrator mounting system, with various parts broken away,
omitted, or shown in section for clarity;
FIG. 2 is an enlarged, fragmentary, exploded, isometric view;
FIG. 2B is an enlarged exploded, fragmentary isometric view of the
preferred strip dampening system;
FIG. 3 is an enlarged, fragmentary sectional view taken generally along
line 3--3 of FIG. 1 showing a single deck only;
FIG. 4 is an enlarged, fragmentary, sectional view taken generally along
line 4--4 of FIG. 2;
FIG. 5 is an enlarged, fragmentary, sectional view taken generally along
line 5--5 of FIG. 2;
FIG. 6 is an enlarged, exploded, isometric assembly view of the preferred
vibrator mounting system;
FIG. 7 is an enlarged sectional view taken generally along line 7--7 of
FIG. 6;
FIG. 8 is an enlarged, fragmentary sectional of the screen rails;
FIG. 9 is a diagrammatic plan view showing typical force distribution along
the top of a conventional prior art vibrating screen;
FIG. 10 is a diagrammatic plan view showing force distribution along the
top of our prior art vibrating screen; and,
FIG. 11 is a diagrammatic top plan view of the vibrating screen of our
invention, showing the novel force distribution characteristics achieved.
DETAILED DESCRIPTION OF THE DRAWINGS
With initial reference now directed to FIG. 1 of the appended drawings, a
screen separator machine constructed according to the teachings of the
present invention has been generally designated by the reference numeral
20. As a preliminary matter it should be appreciated that the systems we
have developed can be applied to many different configurations of
vibrating separator machines involving multiple decks and serially
connected sections. Therefore machine 20 is illustrative of but one
possible machine configuration.
A three section multiple deck separator 20 comprises a rigid, elongated
frame, generally designated by the reference numeral 22, which is somewhat
in the form of a parallelepiped. Frame 22 is supported by a plurality of
vertically upright stanchions 24, 26, and 28 above a lower supporting
surface 30. Surface 30 is normally concrete. Stanchion foot plates 29 can
be firmly bolted into the concrete surface 30 with conventional screws.
Separator 20 is inclined, preferably at approximately 30 to 40 degrees, so
that material entering the material input end 38 through the material
input chute 39 gravitationally flows towards the material discharge end,
generally designated by the reference numeral 42.
As will be recognized by those skilled in the art, machine 20 is a
multi-deck machine, in that a first plurality of aligned, separating
screens are disposed on top, i.e., along row 46, and a second plurality of
vibrating sifting screens are disposed below in row 48. Separator 20
comprises three serially aligned vibrator stations, generally designated
by the reference numerals 49, 50, and 51, which are transversely mounted
over the top 52 covering the upper deck 46. Each vibrator station
preferably comprises a conventional rotary electric vibrator applying
approximately 1000-3000 pounds of unbalanced force, powered with
three-phase alternating electric current at 1500-3600 rpm.
Thus in the disclosed configuration, three sequential screen systems are
employed in each of two decks disposed within the frame to sift and
separate material flowing through the apparatus. Material that does not
drop through any of the screens in the upper deck can be conveyed as
desired through output chute 56. Material that drops through the first
deck but which does not drop through the second deck 48 is outputted
through a chute 58. Material that drops through both decks collects in a
conventional hopper generally designated by the reference numeral 60,
which is disposed beneath the frame. The lower hopper 60 includes a
conventional flange 62 for conventionally outputting fine grade material.
With additional reference directed now to FIGS. 2, 2B and 3, our tuned
suspension system for controlling the sifting screen has been generally
designated by the reference numeral 70. Tuned suspension system 70 is
ideally adapted for implementation in conjunction with the dynamic
vibrator drive system 72 (FIGS. 4, 6). The vibrator drive system 72 and
the tuned suspension system 70 function harmoniously to generate the goals
and objects discussed previously herein. With the multi-deck, sequential
separator machine 20, three separate suspension systems 70 are employed on
each deck (for a total of six), and three separate vibrator drive systems
72 are employed. The number of vibrator drive systems 72 and tuned
suspension systems 70 may be combined and deployed in different
configurations as desired by the application. As will be recognized by
those skilled in this art, the specific configuration depends upon the
number of machine sections and decks employed.
With primary reference directed to FIG. 2, that portion of frame 22 shown
is merely a fragment of the entire frame. The rigid upright frame is
somewhat box-like, and it is generally in the form of a parallelepiped.
Frame 22 comprises a pair of rigid, channel side members 81, 82 that are
spaced apart by suitable channel ends 83. A hollow, generally rectangular
screen receptive region, generally designated by the reference numeral 85,
is bounded by the frame sides 81 and 82 and by frame end 83. A sifting
plane is normally established by the cloth disposed within the region 85
bounded by the frame members. The frame cover 52 (FIG. 1) comprises
generally planar metallic sheet segments 86 that are braced and secured by
elongated cover braces 87, which extend longitudinally along the top of
cover 52 and are fastened to the sides of frame 22.
A sifting plane has been generally designated by the reference numeral 90
(FIG. 2). It preferably comprises a planar, metallic cloth mesh screen 92
tensioned as hereinafter described. A lower sifting plane 90B comprising
screen 92B is disposed beneath the upper deck, and is partially shown in
FIG. 2. In the best mode a generally rectangular subframe 96 is precisely
fitted to the frame interior between frame sides 81 and 82. The subframe
insures that the frame sides do not deform in response to cloth
tensioning, and that they are spaced apart properly. When the screen cloth
is tensioned the subframe resists frame deformation and insures that the
wire cloth is tensioned uniformly. Subframe 96 is conformed to fit within
frame region 85 nestled against the frame side members. Subframe 96
comprises a transverse material input end 98 spaced apart form a parallel
material discharge end 99. Ends 98 and 99 transversely extend between
rigid subframe sides 100 and 101. Intermediate cross braces 103, 104
further strengthen the subframe.
Importantly, the subframe ends 98, 99 are associated with a tuned
suspension system for controlling ends of the screen center vibrating
strip 118. When numerous subframes are sequentially aligned, a gradual
transition between subframes is aided by a cover strip 106 that extends
between serially aligned subframes.
Both screens 92 and 92B are comprised of a resilient, planar wire cloth.
The outermost edges of the screen sides are folded and crimped within
elongated hook strips 93 of generally U-shaped cross section (FIG. 8).
Strips 93 are a secured by suitable tensioning rails 94 to the internal
frame sides. Rail foot 95 fits within the hollow interior of the hook
strip 93, so that lateral displacements f rail 94 towards or away from the
frame tensions or relaxes the screen cloth. As best seen in FIGS. 3 and 8,
the screen is held by the opposite rails 94 positioned within screen
region 85. The rails are retained by carriage bolts 111 threadably engaged
by numerous eye nuts 109 mated to the shafts of the carriage bolts 111
(FIG. 8). Eye nuts 109 are manually adjustable, and they are conveniently
accessible from the frame exterior. The eye nuts 109 may be conventionally
twisted to tighten the screen cloth between inner frame members 81, 82.
The edges of the screen, and the rails 94, mechanically contact the
subframe sides 100, as seen in FIG. 8. The rolled back top edge 114 of the
rail allows it to slide as cloth is tensioned without locking into the
frame sides. This ensures that the tensioning forces applied by the rail
are distributed evenly into the wire mesh. It also insures that terminal
end 113 neither contacts nor wears into the frame sides as vibration
progresses in conjunction with normal operation.
Thus screen 92 extends between the inner sides of the frame within region
85. Of course, the rails 94 previously discussed could alternatively be
associated with the sides 100, 101 of the subframe. The opposite ends of
the screen (i.e., those ends of the screen that overlay subframe ends 98,
99) are not coupled to mounting rails. They are substantially free of
contact with the subframe ends 98, 99 and elevated thereabove. Subframe
end 99 comprises a resilient strip 106 that overlays it to form a smooth
transition to the next sequential subframe. In other words, the overlay
106 covers subframe end 99, and a portion of the next subframe material
receiving end 98 in assembly.
Thus the sides of screen 92 are maintained in tension by the eye nuts 109
that pull the carriage bolts 111 and rails 94. The material input end and
output ends of the screen are not directly mechanically braced.
Importantly the screen comprises an elongated, center vibrating strip 118
that extends longitudinally in the direction of material travel. Strip 118
is substantially centered with respect to the screen, the subframe 96 and
the frame sides 81, 82. Strip 118 comprises a pair of identical,
cooperating, generally rectangular halves 130 and 131 that are bolted
together in aligned relationship with suitable fasteners 139. The halves
130 and 131 are metallic, and they are coupled together by the fasteners
through aligned orifices 141. As appreciated from FIG. 2, the strip halves
130, 131 are tightly sandwiched about the center of the screen 92. The
lower screen unit in the lower deck comprises a similar center strip 118B
comprised of members 130B, 131B, tightly sandwiched about lower screen
92B.
The critical center strip 118 is directly vibrated to shake the screen 92.
Strip half 130 comprises a bracket 150 having a foot 151 directly secured
to strip 130 by suitable fasteners 152. An upwardly projecting link 153
emanating from foot 151 is connected to a vibrator station, as will
hereinafter be described, through a flat, flexible connector 156.
Connector 156 extends from the vibrator station to vigorously oscillate
the center strip 118 and thus the cloth. A lower bracket 158 attached to
the lower half 131 of strip 118 comprises a tab 159 projecting downwardly
into contact with an apertured connector link 160 suitably fastened to tab
153 on the lower bracket 150B (FIGS. 2, 4). Bracket 150B is affixed to
lower vibrating center strip 118B at the lower deck. For additional deck
levels additional links corresponding to links 160 can be interconnected
with lower screens. Each link is lightweight, flat and flexible. Thus
vibrations imparted from the upper vibrator station directly to the
vibrating strip 118 are linked downwardly to the lower subframe screen(s)
92B through the connector apparatus 160.
Importantly, the extreme ends strip halves 130, 131 are resiliently secured
to the subframe ends 98, 99 by a buffer system 170 (FIG. 2, 2B). The strip
buffer system 170 preferably comprises a pair of generally cylindrical,
rubber buffers 172, 174 mounted in shear. For sifting applications
involving material 225 degrees F. or hotter, the buffers comprise
similarly-shaped cylindrical springs with threaded ends. The buffers are
preferably secured by suitable fasteners 175 to the subframe ends 98 and
99. These buffers are similar to that illustrated in FIG. 7.
Each buffer 172, 174 comprises a substantially cylindrical resilient rubber
core 172B, terminating in identical, circular metallic ends 178 that are
vulcanized to the rubber. The ends 178 comprise central, threaded bosses
179 provided for threadable reception of fasteners 175. The suspension
system thus contemplates the resilient coupling of the vibrating strip
opposite ends to the subframe and/or the frame. The buffers 172 and 174
could be mounted directly to the frame ends or mounted to the subframe. An
elongated mounting plate 184 is secured via fasteners 88 (FIG. 2B) through
orifices 186 in plate 184 to orifices 188 in the buffers 172, 174. An
integral tab 190 projecting from plate 184 comprises a stud 191 that
penetrates orifice 192 in vibrating strip 118 for threadable attachment of
nut 193. In this manner the ends of the strips are resiliently coupled to
the frame and to the subframe.
With concurrent reference now directed to FIGS. 2 - 6, the vibrator drive
system 72 is preferably mounted to a transverse bridge 200 disposed on top
of the frame. Bridge 200 is generally flat, but it can be arched. The
bridge extends between the frame side rails 81, 82 above the sifting
plane. As best seen in FIG. 6, the rigid bridge 200 is generally
rectangular in plan, and it comprises suitable end feet 202 adapted to be
coupled to the frame side rails 81 or 82, and side flanges 204, which
integrally interconnect with the frame cover 52. The bridge supports the
vibrator drive system 72, and functions in cooperation with the cover 52
to seal the apparatus from dust.
The vibrator drive system 72 comprises a ruggedized electric, rotary
vibrator 53 designed for twenty-four hour operation. Vibrator 53 comprises
a rigid, generally cylindrical casing 211 in which an eccentrically
weighted internal shaft (not shown) rotates about an axis of rotation 212
aligned with the direction of material travel (FIG. 6). The conventional
eccentric weights are adjustable so the output force can be varied.
Housing 211 is braced by a pair of spaced apart mounting blocks 213 having
cylindrical, orificed feet 215 adapted to be firmly secured to a first
mounting plate, generally designated by the reference numeral 218 (FIG.
6).
The drive system is uniquely designed so that the motor is mounted in shear
by a plurality of rubber buffers. The shear mounting allows the vibrator
motor to produce the required vibration with a minimum of eccentric weight
as opposed to compression mountings on steel springs. The entire drive is
thus quieted and lightened. In the best mode three buffers are mounted on
the "down hill side" and one buffer is mounted at the "up hill side" to
compensate for asymmetrical loading created by the inclined orientation.
The first mounting plate 218 comprises a rigid, generally square plate
member 220 that has been welded to a lower folded member 222 that
comprises a first, downwardly projecting flange 223 and a second
downwardly projecting flange 224. Flanges 223, and 224 are substantially
parallel with one another, and the plane occupied by first and second
flanges 223, 224, respectively is generally perpendicular to the axis of
rotation 212. The first mounting plate 218 is dynamically linked to the
second mounting plate 230; the rubber buffers between the flanges of the
plates are mounted in shear. Second mounting plate 230 is directly secured
upon the top 200A of the bridge 200. It comprises a pair of spaced apart
flanges 233 and 234 which respectively mate with flanges 223 and 224
previously discussed. Flange 233 is hereinafter referred to as the "third
flange;" Flange 234 is hereafter referred to as the "fourth flange." The
flanges 233 and 234 are integral with a base plate portion 237. Base 237
comprises an elongated central slot 238 that allows connector 156 to
extend therethrough.
Both flanges 233 and 234 occupy planes that are substantially parallel to
the planes occupied by flanges 223, 224 The latter planes are also
generally perpendicular to the axis of rotation 212. The second flange 224
is longer and comprises a bigger area than that of flange 223. Similarly,
the fourth flange 234 is longer and of a greater area than third flange
233. As best viewed in FIG. 2, the first and third flanges 223, 233
respectively point at the material input end 38 of the separator, and the
second and fourth flanges 224, 234 are aimed at the material discharge
end. As best viewed in FIG. 5 buffers 240B and 240C are paired together
and offset slightly from buffer 240A to resist torsional forces imposed
from vibrator motor rotation.
Flange 224 is preferably dynamically interconnected with flange 234 by a
trio of cylindrical, rubber drive support buffers 240A-240C secured by
suitable screws 246. The configuration of the buffer array comprising
buffers 240A-240C and an opposite, lesser number of buffers 244 is herein
referred to as "asymmetric." A lesser number of buffers 244 unite the
first and third flanges 223 and 233. Buffers 240A-240C, 244 are of a
larger diameter than buffers 172, 174 previously discussed, and they are
seen in cross section in FIG. 7. Thus the vibrator 53 is dynamically
isolated from the bridge 200 and thus the frame by the buffer array.
Buffers 240A-240C and 244, isolate vibrations from the frame, subframe,
and bridge 200.
Most vibrational energy is transmitted to the connector 156, which is
attached underneath vibrator plate 220 to integral, downwardly projecting
tab 219 (FIG. 4), and from thence to the center plate 218 on the cloth via
connectors 156, 160. Energy is conducted downwardly through the lower
mounting plate 230 through slot 238 and through bridge 200 to directly
contact the vibrating strip 118, secured centrally on the vibrating cloth.
The isolating action of the motor mount buffers keeps vibrations from
setting up a destructive wave causing the motor to expend energy with
rotational motion and flexing the connecting arm to the point of metal
fatigue and failure. More of the available sign wave energy is therefore
transmitted via the connecting arm to the separator screen. The similar
buffers 172, 174 mounting each end of the screen strips to the frame (FIG.
2B) return the longitudinal sign waves at the terminus of their travel at
the screen and cause a return wave of approximately one half the intensity
of the wave at its origin. This smoothing effect helps to reduce the
bounce and toss which is contrary to efficient material screening.
With reference now to FIGS. 9-11, FIG. 9 shows a conventional, prior art
screen of generally rectangular proportions which has been generally
designated by the reference 300. Screen 300 is vibrated directly by a
central strip 303 that is unterminated at its ends. Vibration is
haphazardly applied through conventional techniques. As a result, force is
concentrated within the generally elliptical region identified by the
reference numeral 308, which is surrounded by a cross hatched region 310
exhibiting substantially less vibrational lesser force.
The device of FIG. 10 comprises a screen 320 vibrated by a central piece
322 that is unterminated, although it is longer than strip 303 of FIG. 9.
Again the region 324 bounded by generally sinusoidal shaped cross hatched
regions 328, 329 exhibits the major force distribution. Regions 328, 329
near the boundaries or sides of the apparatus are not appropriately
vibrated, so that material bunching and clogging may occur along such
separators.
FIG. 11 shows the force patterns obtained through our present design. In
this instance the strip 340 corresponds schematically previously described
vibrating strip 118. Substantially larger regions 343, and 344 are shown
in which vibration is thoroughly distributed. Although smaller, peripheral
edge regions 346, 348 exist wherein vibration is less, it is natural that
less vibration amplitude would exist at the termination edges of the
screen. Central diamond shaped regions 350 of lesser force are of minimal
area, so that the maximal areas 343, 344 accomplish the desired goals and
objectives previously set forth herein.
From the foregoing, it will be seen that this invention is one well adapted
to obtain all the ends and objects herein set forth, together with other
advantages that are inherent to the structure.
It will be understood that: certain features and subcombinations are of
utility and may be employed without reference to other features and
subcombinations. This is contemplated by and is within the scope of the
claims.
As many possible embodiments may be made of the invention without departing
from the scope thereof, it is to be understood that all matter herein set
forth or shown in the accompanying drawings is to be interpreted as
illustrative and not in a limiting sense.
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